It is becoming increasingly desirable to simultaneously transmit and/or receive two or more beams. For example, with the advent of satellite cable communications, there has been a growing interest in simultaneously receiving and/or transmitting multiple signals with a single earth station antenna. This interest has prompted the development of several earth-based, multiple-beam antenna configurations employing fixed reflectors and multiple discrete feeds. Three commonly employed multiple-beam earth station antennas are the spherical-reflector antenna, the torus antenna and the offset-fed parabolic antenna, and offset-fed Cassegrain antenna.
As the viability and use of satellite communications have increased, so has the need to consolidate satellite operations. More particularly, it is quite desirable for a satellite antenna arrangement to have the capability of contemporaneously receiving and/or transmitting multiple beams to and from several earth stations, including both stationary and mobile earth stations. Due in large part to space, weight, mechanical complexity beam separation and stability considerations, the above-noted earth station antennas have not been widely employed for multiple-beam satellite applications, and arrangements employing multiple antenna elements, such as simple dipole arrays, have been developed.
In such satellite antennas, the antenna elements typically cooperate so that through the employment of multiple arrays, multiple-beam operation can be achieved. Despite advances in this relatively new field of endeavor, the goal of further minimizing space, weight, and complexity requirements, while maximizing system flexibility and performance, remains. Accordingly, the present invention is directed to a satellite antenna system wherein multiple-beam operation is achieved through the use of a unique antenna arrangement wherein two or more antenna arrays can be selectively employed to contemporaneously contribute to the contemporaneous transmission and/or reception of one or more beams. As will become apparent to those skilled in the art, such an arrangement allows for minimization of space, weight and componentry requirements, while optimizing system flexibility and performance.